Joaquin has become a hurricane overnight, but whether it moves toward the United States remains highly uncertain and we may not know until Friday or so.

We can be pretty confident that Joaquin will to drift to the west-southwest during the next couple of days, strengthening perhaps into a Category 2 or even 3 hurricane and threatening the Bahamas, before turning north on Friday.

Here are the two most likely scenarios I envision for Joaquin after that.

A graphic artist I am not. (NOAA)

SCENARIO 1

This is the scenario of most concern to the mid-Atlantic states, which brings a possible hurricane to the coast early next week.

Forecast models develop a trough of low pressure over the southeastern United States this weekend, and if the trough is strong enough it could capture Joaquin as it’s moving north this weekend and pull it toward North Carolina or Virginia.

This 500 mb map shows a trough of low pressure (dark blue) and how it could pull Joaquin toward the coast. (Weather Bell)

The best American model, the HWRF, has supported this scenario consistently for a couple of days now, and some of the other models have trended toward this kind of track as well.

At this point, based upon the model guidance, I would rate this scenario as more likely than not, perhaps 60 percent to Scenario 2’s 40 percent.

SCENARIO 2

Under this scenario, as Joaquin begins to move north this weekend, it is not captured by the low over the southeastern United States.

This allows the storm to move north, and then northeast over the open Atlantic Ocean. The operational European forecast model, arguably the best model in the world, has favored this solution for a couple of days.

As a caveat it is worth noting that in additional to the “operational” run of the European model, dozens of other lower resolution simulations are run by the European modelers as well. Many of these show a more westward track, more directly affecting the United States.

EFFECTS

So those are the two scenarios. What of the effects?

With very warm water underneath it and low wind shear through Friday, Joaquin will have ample opportunity to strengthen during the next few days. Intensity models suggest it should become a Category 2 to Category 4 hurricane.

If Joaquin turns toward the United States it is not possible to predict at this time how precisely strong it will be, hurricane intensity forecasting just isn’t that good. But potentially Joaquin could be a 110-mph hurricane, or even a tad stronger.

It is worth noting that Joaquin’s wind field is quite a bit smaller than Sandy’s, so it’s unlikely to push as massive a storm surge into the East Coast. Nonetheless storm tides would still be significant and potentially devastating to the north of the storm’s center. Storm surge and winds could be felt as early as Sunday morning by the East Coast if Joaquin heads that way.

Regardless of the storm’s path, the tropical air mass is setting the stage for potentially historic flooding during the next week.

Joaquin has really organized quickly today, and may soon become a hurricane.

Tropical Storm Joaquin at 2 p.m. CT. (NOAA)

Given that Joaquin is over warm water and wind shear is forecast to decrease slightly I think it’s plausible that this could become a Category 1, 2 or even 3 hurricane in terms of wind speed over the next two or three days.

Steering currents at present are weak, so I think a slow westward drift is most likely during that time frame. Confidence is fairly high in such a motion through Wednesday or Thursday.

It seems clear that Joaquin therefore poses a significant threat to the Bahamas.

WHAT WE DON’T KNOW

We don’t know much about what will happen after two or three days.

What’s not clear is whether an upper-level low pressure system over the southeastern United States will be strong enough to pull Joaquin toward the mid-Atlantic states.

A 500 mb map shows how an upper level low could open a corridor for Joaquin to track into the East Coast. (NCEP)

America’s “best” hurricane model, the HWRF, favors such a scenario and brings Joaquin into Virginia as a strong hurricane early next week.

Other important forecast models, including the European and GFS model, have Joaquin blocked from moving northwest and keep it out to sea. For now, at least, the National Hurricane Center favors the latter scenario, but with “low confidence.”

The unfortunate part of this is that we’re unlikely to know much about the future evolution of Joaquin for a couple of days, as it drifts westward. The models are likely to continue to flop around. Such uncertainty will confound any necessary preparations along the East Coast.

Intensity, too, is a challenge. Although Joaquin is strengthening now, it’s difficult to say how strong it will be in four or five days.

BOTTOM LINE

Residents on the East Coast, from the Carolinas northward, need to pay attention to this system, at least until the forecast becomes more clear.

At a minimum Joaquin is likely to bring some very heavy rains to the mid-Atlantic and northeastern states — some areas could see 12 inches or more — and potentially quite a bit more in terms of wind and surf.

]]>8180NWS posts flood warninghttp://blog.ctnews.com/weather/2015/06/02/nws-posts-flood-warning/
Tue, 02 Jun 2015 10:06:20 +0000http://blog.ctnews.com/weather/?p=8174The National Weather Service has posted a flood warning for the Still River in Brookfield.

The river is already at its 12-foot flood stage.

The NWS says the river is expected to be a half-foot above flood stage before it starts to fall after 9 AM Tuesday.

Showers and possibly a thunderstorm before 9am, then a chance of showers and thunderstorms after 9am. Some of the storms could produce heavy rain. High near 60. Northeast wind 11 to 13 mph. Chance of precipitation is 90%. New rainfall amounts between three quarters and one inch possible.

Tonight

Showers and possibly a thunderstorm. Some of the storms could produce heavy rain. Low around 53. Northeast wind 10 to 14 mph. Chance of precipitation is 90%. New rainfall amounts between 1 and 2 inches possible.

Tuesday

Rain. The rain could be heavy at times. High near 64. North wind 7 to 9 mph. Chance of precipitation is 90%. New precipitation amounts between a half and three quarters of an inch possible.

Tuesday Night

A chance of showers before 8pm. Cloudy during the early evening, then gradual clearing, with a low around 50. Northeast wind 6 to 10 mph. Chance of precipitation is 30%.

Wednesday

Sunny, with a high near 68. Northeast wind around 6 mph becoming southeast in the afternoon.

Wednesday Night

Clear, with a low around 53.

Thursday

Partly sunny, with a high near 71.

Thursday Night

Mostly cloudy, with a low around 57.

Friday

Mostly cloudy, with a high near 74.

Friday Night

A chance of showers and thunderstorms. Cloudy, with a low around 60. Chance of precipitation is 30%.

Saturday

A chance of showers and thunderstorms. Cloudy, with a high near 74. Chance of precipitation is 30%.

“The main factor expected to suppress the hurricane season this year is El Niño, which is already affecting wind and pressure patterns, and is forecast to last through the hurricane season,” said Gerry Bell, lead seasonal hurricane forecaster with NOAA’s Climate Prediction Center.

NOAA hurricane outlook for the 2015 Atlantic season. (NOAA)

One interesting note on El Niño is that while it often dampens activity during the peak months of the Atlantic season – August and September – it has less of an effect on storm development in June and July.

What that means is that Texas could easily be threatened by a rainmaking tropical storm in June or July, something we really don’t need after a very rainy April and May.

In any case, all the usual caveats apply to this hurricane forecast. One, seasonal forecasts are far from perfect. Two, it only takes on hurricane to ruin your year, so quiet year or not it’s best to prepare now for the worst case scenario in a few months.

That means you should know your evacuation zone, where you’d go if called upon to evacuate, and you’re stocked up on supplies.

]]>8183It’s official: Area in a “moderate” droughthttp://blog.ctnews.com/weather/2015/05/26/its-official-area-in-a-moderate-drought/
Tue, 26 May 2015 17:00:45 +0000http://blog.ctnews.com/weather/?p=8153Yes, it’s been a dry spring.

But on Tuesday, the National Weather Service used a term for our weather that has been a buzzword in California for months.

And that word is “drought.”

While conditions here are nothing like what much of the West Coast is facing, and there are no water shortages or restrictions, meteorologists said Tuesday that a “moderate drought condition” exists in Connecticut and parts of New York and New Jersey.

Bridgeport has received about 2.5 inches less of rainfall than in a typical May, the National Weather Service said. “The last two months our area has experienced well below normal precipitation,” a NWS Facebook posting said.”… a moderate drought is now underway.”

The U.S. Department of Agriculture has also posted a “moderate” drought advisory for the region.

While it would take a significant rainfall to reverse the trend, the next several days do bring the possibility of showers and thunderstorms.

Here is the extended forecast from the National Weather Service:

Today: Mostly sunny, with a high near 82. Southwest wind around 11 mph.

Tonight: A slight chance of showers and thunderstorms after 3 a.m. Patchy fog after 2 a.m. Otherwise, mostly cloudy, with a low around 63. South wind 5 to 11 mph. Chance of precipitation is 20%.

Wednesday: A slight chance of showers and thunderstorms before 9 a.m. Patchy fog before 9 a.m. Otherwise, mostly cloudy, with a high near 75. South wind 6 to 10 mph, with gusts as high as 21 mph. Chance of precipitation is 20%.

Wednesday Night: A slight chance of showers and thunderstorms. Mostly cloudy, with a low around 64. South wind 7 to 11 mph. Chance of precipitation is 20%.

Thursday: A chance of showers and thunderstorms, mainly after noon. Mostly cloudy, with a high near 76. South wind 6 to 9 mph. Chance of precipitation is 40%.

Thursday Night: A chance of showers and thunderstorms, mainly before 10pm. Mostly cloudy, with a low around 62. Chance of precipitation is 30%.

Friday: Mostly cloudy, with a high near 75.

Friday Night: Mostly cloudy, with a low around 62.

Saturday: Mostly sunny, with a high near 77.

Saturday Night: A chance of showers and thunderstorms. Mostly cloudy, with a low around 61. Chance of precipitation is 40%.

Sunday: A chance of showers. Mostly cloudy, with a high near 69. Chance of precipitation is 30%.

]]>8153Unusually dry spring, but no drought herehttp://blog.ctnews.com/weather/2015/05/11/unusually-dry-spring-but-no-drought-here/
Mon, 11 May 2015 13:14:11 +0000http://blog.ctnews.com/weather/?p=8150Maybe you’ve noticed that there were fewer April showers than normal and so far May hasn’t brought much rain either.

Although we do not have a drought by meteorological standards and nowhere near the dire water shortage facing California, southern Connecticut has had about 25 percent less rain than the average for spring, according to the National Weather Service.

There is some spotty showers and drizzle coming our way over the next few days, but nowhere near enough to make up the difference, forecasters say.

We’re also going to miss the torrential rains and flooding in the Midwest.

But there is no water shortage here and it might be a good idea to water new plants and bulbs.

Here is the extended forecast from the National Weather Service:

Today: Partly sunny, with a high near 78. South wind 7 to 13 mph.

Tonight: Patchy fog after midnight. Otherwise, mostly cloudy, with a low around 65. South wind 5 to 11 mph.

Tuesday: A chance of showers and thunderstorms, mainly after 3pm. Patchy fog before 9am. Otherwise, mostly cloudy, with a high near 82. Southwest wind 5 to 14 mph. Chance of precipitation is 30%.

Tuesday Night: A slight chance of showers and thunderstorms before midnight. Partly cloudy, with a low around 55. West wind 8 to 10 mph. Chance of precipitation is 20%.

Wednesday: Mostly sunny, with a high near 66. Breezy, with a northwest wind 11 to 20 mph, with gusts as high as 31 mph.

Wednesday Night: Mostly clear, with a low around 44.

Thursday: Sunny, with a high near 67.

Thursday Night: Mostly clear, with a low around 47.

Friday:Sunny, with a high near 69.

Friday Night: Mostly cloudy, with a low around 51.

Saturday: A chance of showers. Mostly cloudy, with a high near 68. Chance of precipitation is 30%.

Saturday Night: Mostly cloudy, with a low around 53.

Sunday: Partly sunny, with a high near 69.

]]>8150Weather alert: A bad air day todayhttp://blog.ctnews.com/weather/2015/05/08/its-going-to-be-a-bad-air-day-today/
Fri, 08 May 2015 10:17:42 +0000http://blog.ctnews.com/weather/?p=8145

Here’s a short weather lesson: how sea breezes happen.

The state Department of Energy and Environmental Protection has issued a air quality alert for northern Fairfield and New Haven counties.

The alert is in effect from 11 AM to 11 PM.

“An air quality action day means ozone levels within the region may approach or exceed unhealthy standards.” the alert says. “Unhealthy levels of ozone can affect anyone, particularly sensitive groups that include children, the elderly, people with respiratory disease, such as asthma and even healthy adults who are very active outdoors.”

No air alert has been issued for the shoreline because sea breezes are expected to freshen up things nicely.

This morning we have thick fog along the immediate coast, caused in part by the combination of cool water temperatures in Long Island Sound and warmer air temps.

Morning fog is also expected Saturday and Sunday mornings; it is expected to burn off by 9 AM.

The weekend weather is looking good with sunny skies and temperatures in the 80s.